Process of making reinforced tubes or pipes



1939. A. J. BERG ET AL 2,145,244

PROCESS OF MAKING REINFORCED TUBES' OR PIPES Filed Feb. 14, 1936 E/5% JBea BY Jan 0. 2/05:-

ATTORNEY Patented Jan. 31, 1939 UNITED STATES PROCESS OF MAKINGREINFORCED TUBES OR PIPES Alfred J. Berg and John 0. Huse, United StatesNavy, Portsmouth, N. H.

Application February 14, 1936, Serial No. 63,896

1 Claim.

(Granted under the act of March 3, 1883, as

amended April 30, 1928; 370 0. G. 757) Our invention relates to areinforced pipe or tube and the method of producing the same.

The object of our invention is to provide a. reinforced pipe or tubewith a reinforcement which shall not impair in any respect the strength,resistance to pressure, corrosion and other deterioration that may beencountered in use, and

which will increase the efficiency of the pipe or tube to which the samemay be applied and at a moderate cost of production.

The further object of our invention is to provide the reinforcement ofsuch character and structure that the same may conform to the foregoingobjects.

A further object of our invention is to provide a process for theconvenient commercial economical production of the reinforced pipe ortube in accordance with our invention, and which method may be practicedby hand or by any of a number of different machines with or withoutsubstantial modification.

Further objects will become apparent from familiarity with thespecification. 4

In the drawing in which like characters of reference indicate the sameparts,

Fig. l is a plan view of a portion of a tube constructed in accordancewith our invention;

Fig. 2 is a magnified cross-sectional view of a portion of ourreinforced tube;

Fig. 3 is a view similar to Fig. 2 but showing a foot in both sides ofthe reinforcing strip at its inner edge.

Fig. 4 is an illustration in central vertical sectional elevation of ameans for performing the act of splitting the edge of the reinforcingstrip adjacent to the pipe or tube.

In the drawing, I0 represents the pipe, tube, or other hollow body to bereinforced, and II represents the reinforcing strip. The reinforcingstrip is formed usually from a flat thin wide strip of metal whose edgeadjacent the pipe or tube is slightly turned over to form a shoulder incontact with the exterior surface of the tube. Such turned over edge isat its end secured to the surface of the tube by solder to a slightextent. The amount turned over at the inner edge of the fin is but avery small portion of the width of the initial fiat reinforcing strip.This bent over shoulder is progressively formedon the inner edge of thereinforcing strip II simultaneously with and in advance of the pointwhere the flat fin II is progressively bent about the tube or otherhollow member. This bent over portion of the reinforcing strip precludesthe wrinkling of the reinforcing strip at its inner edge as it is beingcoiled about the pipe or tube, and further tends to reduce the liabilityof the formation of such wrinkles by slightly reducing the internaldiameter of the bent or formed reinforcing strip; stiffens the inneredge of the reinforcing strip so as to tend to preclude the formation ofwrinkles therein by reason of and during the bending operation andrequires, for the avoidance of suchtwrinkles, that the neutral axis ofthe reinforcing strip while the same is being formed about the pipe ortubeshall be located longitudinally close to the bent portion I2 of saidstrip II. Relative to said neutral axis there will occur in strip I I,while the same is being formed about the pipe or tube, a compressionstrain in the metal of this strip II toward the surface of the tube IDfrom said neutral axis, while there will likewise occur in the metal ofthe strip I I an elongation or stretching stress between said neutralaxis and the outer edge of the formed or bent strip II. This bent overshoulder I2 may be formed by at least one pair of rollers through whichsaid edge of strip II is passed progressively adjacent to and whilebeing wound upon the outer surface of pipe or tube ID. The pipe or tubeI0 is not thinned or weakened by having formed therein any groove inwhich an edge of strip I I may be inserted and progressively woundtherein and the wall of the pipe or tube I0 is not otherwise weakened.In the coiling or bending of strip II about the pipe or tube II] thebent edge or shoulder I2 of strip II .has a substantial tendency toinduce the bending or winding of the strip II upright. However, somerelatively slight lateral support is required for at least the outeredge of strip II at least at the point where it is being progressivelybent or coiled about the pipe or tube III. The shoulder I2 of strip I Ienables such reinforcment to be coiled about a relatively thin walledtube III without distorting or weakening such wall by the act ofreinforcing such pipe or tube.

At a point preferably beyond the point where the strip II is beingprogressively bent the shoulder I 2 is rolled or thinned slightly and atleast a portion of its area in contact with the tube III is depressedslightly into the outer surface of the thin wall of the pipe or tube I0in order to secure the strip II to the wall of the pipe or tube III byan interrupted or continuous line of such depression or interlocking ofthe metal of the strip and the tube together extending parallel with thestrip II and within the area of the shoulder I2.

Instead of forming the shoulder I2 solely upon .edge of strip I I.

one side of the strip I I while the sameis being formed or bent aboutthe tube I0, shoulders I2a may be formed on opposite sides of the innerOne convenient and inexpensive manner of forming said opposite extendingshoulders I2a being shown in Fig. 4 in which the straight strip II ispassed through a block or roller I5 having a slot extending therethroughprovided with a flaring outer edge, and into which flaring edge entersthe bifurcating edge of a knife or roller I6 which bifurcates theadjacent edge of strip I I without the loss of any metal content of theportion of the strip II which is so bifurcated. This operation isperformed preferably continuously with and in advance of the coiling ofthis strip about the tube. The force required to coil the strip aboutthe tube will spread said bifurcation and laterally extend the shoulders[2a from opposite sides of strip II during the coiling of strip II aboutthe tube. This lateral extending of shoulders I2a, while the strip II isbeing pressed toward the body portion I0 exerts an abrading action uponand along the outer surface of the body portion in contact with theseparated split edges of the shoulders I2a. This abrading action afiordsa very efficient heat and cold exchange between the body portion III andthe split surfaces of the shoulders or feet In of the strip II byproviding a firm contact between clean metal freed from oxide or otheraccumulated matter, as well as avoids the possibility of invitingcorrosion between the thus contacted surfaces. At a point subsequent tobut continuous with the bending of the strip II about the tube theshoulders I2a are rolled or otherwise formed into the desired shape andpreferably as a part of said shaping or rolling at least a small portionof the surfaces of shoulders I2a is depressed beneath the exteriorsurface of pipe or tube III to secure the strip to the tube by theinterlocking together of portions of the metal of each of these securedparts in a course substantially continuous along the line of contactbetween said parts.

From the foregoing, those skilled in the art will be enabled to readilymake the thus described reinforced pipe and to understand and practicethe method of making the same, by hand, as well as by a number ofdifferent machines with or without substantial modification afterbecoming familiar with the foregoing.

It will be understood from the foregoing that a very eilicientreinforced pipe or tube is readily produced in accordance with ourinvention of the requisite strength and yet substantially lesser weightand cost more advantageously than has been possible to obtain with priorconstructions.

It will be furthermore understood that the inherent advantages of thereinforced pipe or tube constructed in accordance with our invention ispeculiarly adapted to be very advantageously employed for any purposefor which reiriforced'pipe or tubes may be employed as well as for theexchanging of heat and cold, among other uses. In such latter use thecontact between the exterior and normal surface of the pipe or tube andthe inner surface of the shoulder I2, as well as shoulders Ila, afford avery eflicient heat and cold exchange between the tube I0 and strip II;that the rolling and securing by said interlocking of the metal of theshoulder or shoulders and of thetube increases the rate of heat and coldexchange between the tube and the strip by increasing the density of themetal in the original of the surface of the parts in contact; that itprovides a securement without any open joint in which dust, sediment orother non-conducting matter may be.deposited to impair the rate of heator cold exchange between the parts thus secured together, as well asavoids the possibility of inviting corrosion.

This invention may be made and used by or for the Government of theUnited States for governmental purposes without the payment of anyroyalty therefor.

Having now so fully described our invention that others may therefrommake and use the same, what we claim is:

The method of making a heat exchanging element comprising the steps ofsplitting and partially spreading one edge of a thin rib, disposing saidrib along a surface of the thin walled body portion of the element withsaid split edge of the rib in contact with the surface of the bodyportion, pressing the rib toward and along said body portion with itssplit spread edges laterally abrading the surface of the body portion asthe same are further spread by said pressing, and simultaneously placingthe 'outer and inner portions of said rib respectively under tensionaland compressional stresses, slightly thinning said split edges andfurther spreading the same, and pressing a minor portion of said thinnededges beneath the normal surface of the thin walled body portion.

ALFRED J. BERG. JOHN O. HUSE.

